Electric-arc lamp



D. HIGHAM.

ELECTRIC ARG LAMP.

(No Model.)

No. 562,609. Patented June 23, 1896.

ANDREW s GRANAM PHOTD LrTHQwAsrflNGTON D C UNITED STATES PATENT OEEIcE.

DANIEL IIIGHAM, OF BOSTON, MASSACHUSETTS.

ELECTRIC-ARC LAM P.

SPECIFICATION forming part of Letters Patent No. 562,609, dated June 23,1896.

Application filed March 3l, 1896. Serial No. 585,607. (No model.)

To all whom t may concern,.-

Be it known that I, DANIEL IIIGHAM, a citi-v zen of the United States,and a resident of Boston, Suffolk county, Massachusetts, have inventedImprovements in Electric Arc Lamps, of which the following is aspecication.

This invention relates to electric-arc lamps, and has for its object toprovide means whereby the life or burning hours of an arc-lamp can beincreased without reducing its lightgiving efficiency or withoutinterfering with the proper distribution of light in the lampglobe, asmore fully described hereinafter.

One way in which the carbon life in an arclamp has been greatlyprolonged has been by inclosing the arc in a nearly air-tight glass bulbor globe, but this, as is well known, greatly reduces the light-givingeliiciency in comparison with an arc-lamp having its carbon pointsburning in the open air. Another means known to the art for increasingthe carbon life in an arc-lamp is to place immediately over the are asort of hood having a hole in its center for the uppercarbon to passthrough and controlled by suitable means to lower the same as the lowercarbon burns away in order that the hood shall be continually heldimmediately over the arc; but in this case, although the lightglvingeliiciency is notnoticeably reduced, thehood casts aheavy shadow in theupper part of the globe, which at the later burning hours of the lampcauses all the light to be in the very bottom of the lamp-globe, andthereby interferes with the proper distribution of light.

It is the object of this invention, however, to make use of thesecond-described means of increasing the carbon life in an arc-lamp andto overcome the objectionable feature of having to lower the hood downin the globe with the burning away of the lower carbon and theconsequent improper distribution of light, by fixing the hood stationaryto the lamp-frame and provide means for feeding up the vlower carbon inexact relation to the hood, as will be best understood from theaccompanying drawings, in which- Figure l represents the globe and lowerpor tion of the lamp-frame of an ordinary arc lamp having my inventionapplied thereto,

while Fig. 2 shows in plan view, drawn to a larger scale, the lowercarbon and its holder.

In Fig. l, A is the upper carbon to be controlled by suitable feedingmechanism in the usual manner. E is the lower portion of the lamp-frame,forming part of which is a bridge L, supporting a hood M, shown incross-section. This hood is intended in the present instance to be ofporcelain or other insulating material capable of withstanding a highdegree of heat, and encircles and lits closely around the upper carbonimmediately above the are. Fixed to frame E is a tube O, electricallyinsulated from the frame by an insulation e. An insulated conductor Fconnects the tube O to the negative terminal of the lamp in the usualmanner of forming the circuit to the lower carbon. B is the lower ornegative carbon, which is free to move in the tube O, but is preventedfrom passing upward and out through the same by teats or holdingfingersc, driven in or otherwise secured to or formed ou the tube O, as shownin the drawings. These teats should be of platinum or other suitablematerial capable of withstanding a high degree of heat and shouldproject slightly inward over the edge of the lower carbon point, asshown in Figs. l and 2.

II is a spring' compressed for tension to push the lower or negativecarbon B upward against the holding-fingers c, and is held incompression by a cap G, electrically insulated from the spring II by aninsulation g. The lower carbon can. be removed when necessary by takingoff cap Gr and withdrawing the spring H.

The lamp-globe K isheld by a suitable holder lo.

The operation of my invention will, of course, be apparent, for it willbe seen that as fast as the lower carbon burns away at the point thespring II will push the same up against the holding -ingers c, andthereby cause the arc to maintain an exact relation to hood M andcontinually give a proper distribution of light in the lamp-globe,inasmuch as the hood M will rem ain stationary with the lamp-frame. Fromactual trial runs I have found this means to work very satisfactorilyand to increase the carbon life about double that of a purely open-airarc-lamp and to give equally as good alight-giving eiiiciency.

IOO

I am aware that an are-lamp has been provided with a chamber around thecarbon points, with openings up through and out of the top of thechamber, and that an arc-lamp has been provided Wit-ha covering abovethe are but with a hole in its center large enough for the upper carbonto pass through without contact. Such devices, although perhaps usefulfor the purposes for which they were intended, would have littlecarbon-saving qualities, since the gas formed by the arc would readilypass up through and out of such openings and leave the arc surrounded byoxygen.

In my lamp the hood closely its the upper carbon and is without openingsleading from the arc up through and out of its top, and it is to deiinesuch a construction that I use the term closed hood in my claim.

I claim as my invention- An electric-arc lamp provided with a frame andan upper carbon adapted to be fed down by suitable means, in combinationwith a closed hood iXed stationary with the lampframe, said hood closelyfitting and encircling the upper carbon immediately above the arc,

DANIEL HIGIIAM.

NVitnesses:

A. N. BONNEY, C. G. GRAYDON.

